The DNA sequence of the gene 23 which codes for major structural protein of bacteriophage T4 is being determined by the technique of Maxam and Gilbert. So far more than one-half of the sequence has been revealed. Using this information we have compared the nucleotide sequence with the amino acid sequence that is partially known. We are also determining the starting point of the major gene 23 message. It appears to lie within the neighboring structural gene 22. Further work will be aimed at determining whether or not this site is the actual starting point of transcription for gene 23 or a processing site.